PDF(Pubmed)
Abstract：
BACKGROUND: Pedicle screw loosening and breakage are common causes of revision surgery after lumbar fusion. Thus, there remains a continued need for supplemental fixation options that offer immediate stability without the associated failure modes. This finite element analysis compared the biomechanical properties of a novel cortico-pedicular posterior fixation (CPPF) device with those of a conventional pedicle screw system (PSS).
METHODS: The CPPF device is a polyetheretherketone strap providing circumferential cortical fixation for lumbar fusion procedures via an arcuate tunnel. Using a validated finite element model, we compared the stability and load transfer characteristics of CPPF to intact conditions under a 415 N follower load and PSS conditions under a 222 N preload. Depending on the instrumented levels, two different interbody devices were used: a lateral lumbar interbody device at L4-5 or an anterior lumbar interbody device at L5-S1. Primary outcomes included range of motion of the functional spinal units and anterior load transfer, defined as the total load through the disk and interbody device after functional motion and follower load application.
RESULTS: Across all combinations of interbody devices and lumbar levels evaluated, CPPF consistently demonstrated significant reductions in flexion (ranging from 90 to 98%), extension (ranging from 88 to 94%), lateral bending (ranging from 75 to 80%), and torsion (ranging from 77 to 86%) compared to the intact spine. Stability provided by the CPPF device was comparable to PSS in all simulations (range of motion within 0.5 degrees for flexion-extension, 0.6 degrees for lateral bending, and 0.5 degrees for torsion). The total anterior load transfer was higher with CPPF versus PSS, with differences across all tested conditions ranging from 128 to 258 N during flexion, 89-323 N during extension, 135-377 N during lateral bending, 95-258 N during torsion, and 82-250 N during standing.
CONCLUSIONS: Under the modeled conditions, cortico-pedicular fixation for supplementing anterior or lateral interbody devices between L4 and S1 resulted in comparable stability based on range of motion measures and less anterior column stress shielding based on total anterior load transfer measures compared to PSS. Clinical studies are needed to confirm these finite element analysis findings.
METHODS: The CPPF device is a polyetheretherketone strap providing circumferential cortical fixation for lumbar fusion procedures via an arcuate tunnel. Using a validated finite element model, we compared the stability and load transfer characteristics of CPPF to intact conditions under a 415 N follower load and PSS conditions under a 222 N preload. Depending on the instrumented levels, two different interbody devices were used: a lateral lumbar interbody device at L4-5 or an anterior lumbar interbody device at L5-S1. Primary outcomes included range of motion of the functional spinal units and anterior load transfer, defined as the total load through the disk and interbody device after functional motion and follower load application.
RESULTS: Across all combinations of interbody devices and lumbar levels evaluated, CPPF consistently demonstrated significant reductions in flexion (ranging from 90 to 98%), extension (ranging from 88 to 94%), lateral bending (ranging from 75 to 80%), and torsion (ranging from 77 to 86%) compared to the intact spine. Stability provided by the CPPF device was comparable to PSS in all simulations (range of motion within 0.5 degrees for flexion-extension, 0.6 degrees for lateral bending, and 0.5 degrees for torsion). The total anterior load transfer was higher with CPPF versus PSS, with differences across all tested conditions ranging from 128 to 258 N during flexion, 89-323 N during extension, 135-377 N during lateral bending, 95-258 N during torsion, and 82-250 N during standing.
CONCLUSIONS: Under the modeled conditions, cortico-pedicular fixation for supplementing anterior or lateral interbody devices between L4 and S1 resulted in comparable stability based on range of motion measures and less anterior column stress shielding based on total anterior load transfer measures compared to PSS. Clinical studies are needed to confirm these finite element analysis findings.
摘要：
背景：椎弓根螺钉松动和断裂是腰椎融合术后翻修手术的常见原因。因此，仍然持续需要提供即时稳定性而没有相关故障模式的补充固定选项。此有限元分析比较了新型皮质椎弓根后路固定（CPPF）装置与常规椎弓根螺钉系统（PSS）的生物力学特性。
方法：CPPF装置是一种聚醚醚酮带，通过弓形隧道为腰椎融合手术提供周向皮质固定。使用经过验证的有限元模型，我们将CPPF的稳定性和载荷传递特性与415N跟随器载荷下的完整条件和222N预载荷下的PSS条件进行了比较。根据仪表水平，使用了两种不同的体间装置：L4-5的外侧腰椎体间装置或L5-S1的前腰体间装置。主要结果包括脊柱功能性单位的活动范围和前部负荷转移，定义为功能运动和跟随器负载应用后通过磁盘和体内设备的总负载。
结果：在评估的所有椎间装置和腰椎水平的组合中，CPPF始终显示出屈曲的显着降低（范围从90％到98％），扩展(范围从88%到94%)，横向弯曲（范围从75％到80％），与完整的脊柱相比，扭转（77％至86％）。在所有模拟中,CPPF装置提供的稳定性与PSS相当(屈伸运动范围在0.5度内,侧向弯曲0.6度，和0.5度的扭转）。与PSS相比，CPPF的前负荷转移总量更高，在屈曲过程中，所有测试条件的差异范围从128到258N，89-323N在延伸过程中，135-377N横向弯曲，扭转时95-258N,站立时82-250N。
结论：在建模条件下，与PSS相比，用于补充L4和S1之间的前部或外侧椎间装置的皮质椎弓根固定基于运动范围的稳定性相当，并且基于总的前部载荷转移措施的前柱应力屏蔽较少。需要临床研究来证实这些有限元分析结果。
方法：CPPF装置是一种聚醚醚酮带，通过弓形隧道为腰椎融合手术提供周向皮质固定。使用经过验证的有限元模型，我们将CPPF的稳定性和载荷传递特性与415N跟随器载荷下的完整条件和222N预载荷下的PSS条件进行了比较。根据仪表水平，使用了两种不同的体间装置：L4-5的外侧腰椎体间装置或L5-S1的前腰体间装置。主要结果包括脊柱功能性单位的活动范围和前部负荷转移，定义为功能运动和跟随器负载应用后通过磁盘和体内设备的总负载。
结果：在评估的所有椎间装置和腰椎水平的组合中，CPPF始终显示出屈曲的显着降低（范围从90％到98％），扩展(范围从88%到94%)，横向弯曲（范围从75％到80％），与完整的脊柱相比，扭转（77％至86％）。在所有模拟中,CPPF装置提供的稳定性与PSS相当(屈伸运动范围在0.5度内,侧向弯曲0.6度，和0.5度的扭转）。与PSS相比，CPPF的前负荷转移总量更高，在屈曲过程中，所有测试条件的差异范围从128到258N，89-323N在延伸过程中，135-377N横向弯曲，扭转时95-258N,站立时82-250N。
结论：在建模条件下，与PSS相比，用于补充L4和S1之间的前部或外侧椎间装置的皮质椎弓根固定基于运动范围的稳定性相当，并且基于总的前部载荷转移措施的前柱应力屏蔽较少。需要临床研究来证实这些有限元分析结果。
